Table Of Content)
2008. The Journal ofArachnology 36:609-611
SHORT COMMUNICATION
Snatching prey from the mandibles of ants, a feeding tactic adopted by East African jumping spiders
Robert R. Jackson: International Centre for Insect Physiology and Ecology, PO Box 30772, Nairobi, Kenya & School of
Biological Sciences, University of Canterbury, Private Bag 4800, Christchurch, New Zealand
Kathryn Salm: School of Biological Sciences, University of Canterbury, Private Bag 4800 Christchurch, New Zealand
Simon D, Pollard': Canterbury Museum, Rolleston Avenue, Christchurch 8013, New Zealand
Abstract. Instancesaredocumented ofsalticidsrobbingantsbyadoptingaspecialized behaviorpattern, “snatching.”The
salticid positioned itselfbeside an ant column on the wall ofa building, repeatedly fixating its gaze on different individual
ants in the column and maintaining fixation on the ant by turning its body while the ant walked by. When close to an ant
that wascarrying prey, thesalticid maneuvered about so that it was head on, grabbed hold ofthe preyusing itschelicerae,
and then rapidly pulled the preyout oftheant’smandibles. Havingsecured the prey, thesalticid moved away from theant
column to feed. All observations were made at Mbita Point, by the shore ofLake Victoria in western Kenya. The salticids
werethreespeciesofMenemerus(Simon 1868): M. bivittatus(Dufour 1831), M. congoensisLessert 1927andan undescribed
species, Menemerussp. n. The ant specieswere from thegenera Crematogaster(Lund 1831) and Camponotus(Mayr 1861).
mm
In all instances, the salticid was 2-6 in body length (juveniles ofall three Menemerusspecies and adults ofMenemerus
sp. n). Prey items taken from ants were, in most instances, “lake flies” (adults ofChaoboridae and Chironomidae).
Keywords: Salticidae, ants, predation, stealing prey, Chironomidae, Chaoboridae
In the tropics, ants (Formicidae) are the dominant insects METHODS
(bthHeeoglidlndonoimbnilgneartnot&usnpWdiiedrlessrtosann(dC1o9hd9od0)iwngastanlodtnicji&udmspLaiennvdigas1n9pt9is1d)ei,rnstbeu(rtSaacltwtei(cNiaedrlaees)oonnalr&ye tohbesMeerAnvfeartmiiceoarnnussswpieescraieesloarnygeet,M.wteolblib-veditetFdaietnsuecsdri(gbDeeundufso(,uWrpers1oo8bl3ao1b)wl,sykMaw.it1hc99om9n)ga.oneynOsuiorsf
Jackson 2005, 2006a,b; Nelson et al. 2006). Salticids are unique (Lessert 1927) and a new, undescribed species, Menemerus sp. n. all
&va1i9ms9oiJ0)noa,ncg-kegssxupociineddpeetd2ri0sop0nbr4a)eel.cdlaaytuMaosocresuyttoefbesvthpihaeescviiirioenocsro(mLi(npaJlantcedhkxis&soenyNleais&rlgs(esPLooafnlnald2ma0irl0d1y29)6199(a;9an6bB;dolueHitsnattrr5eli,tca0ana0tld0e. bTtVihyovrpuieitcecthaaotelufrs,wbshopi1de0ccyhimmmalere;nensgctMoho.fsmamlcoloofnsngpoaeedicnunisleiEtssa,sfftre7omAmamflrmteihs;ciasoMs(fetseuneedeyaJmcae(hcsrakulsstspoiecnicsdips1.e,9s8na6.na,trse51,:9m9am9Mn)..d.
described species, Platnick 2008)appearto beactivehuntersthat prey prey) have been deposited with the Florida State Collection of
primarily on a variety of insects, but typically they do not prey on Arthropods in Gainesville and the National Museums of Kenya in
ants. It may not be surprising that many salticid species can detect Nairobi.
antsbysight and then avoid comingcloseto them (Nelson &Jackson Our study site was by the shore ofLake Victoria in western Kenya
2006c), particularly considering the formidable defences shown by (Mbita Point, the Thomas Odhiambo Campus of the International
ants (Blum 1981; Holldobler & Wilson 1990), including powerful Centre for Insect Physiology and Ecology). Mbita Point is 1200 m
mandibles, poison-injecting stings and formic-acid sprays, and the above sea level (0°25'S-0°30'S, 34°10'E-35°15'E) and has a mean
factthatantsaresometimespredatorsofsalticids(Nelsonetal. 2004). annual temperature of 21° C. In this habitat, midges (Diptera:
Yet there is a large minority of salticids (the “myrmecophagic Chironomidae & Chaoboridae), known locally as “lake flies,” are
species”) that selectsantsaspreferred prey(Li&Jackson 1996; Clark exceedingly abundant (Beadle 1981), often covering the walls of
et al. 2000; Jackson & Li 2001; Huseynovet al. 2005) and one salticid buildings. As midges have notoriously short life spans, lake-fly
species, Cosmophasis bitaeniata (Keyserling 1882), is known to swarmsquicklyturnintoenormousnumbersoflake-flycorpseswhich
combine chemical ant mimicry with myrmecophagy (Allan & Elgar are routinely scavenged by ants.
2001)(i.e., bymimickingthecuticularhydrocarbonsoftheAustralian Weopportunisticallyobserved Menemerusandothersalticidswhen
weaver ant, Oecophylla smaragdina (Fabricius 1775), C. bitaeniata they were seen in the vicinity ofants on building walls. Whenever we
gainsentry totheweaverant’s nest and feeds unmolested o—n theant’s sawasalticid persistentlyorienting toward an ant (identified to genus
larvae). Here we revisit a different style ofexploiting ants robbing only), we continued observation for 30-60 min or until the salticid
ants ofobjects they carry in their mandibles. This was First described secured the prey. First we madeabout 30 preliminary observations of
by Bhattacharya (1936) who observed juveniles of Menemerus Menemerus sp. n. snatching lake flies from an unidentified species of
bivattatus (Dufour 1831) (formerly Marpissa melanognathus in India Crematogaster(Lund 1831), butwith no attempt made to identify the
grabbing food out ofthe mandibles ofFire ants, Solenopsisgeminata lake fly to family and no records kept concerning the salticid other
(Fabricius 1804). Our own observations show that this tactic, which than the species to which it belonged. We videotaped 10 of these
we will call “snatching from ants” orjust “snatching,” for short, is preliminary observations for more detailed information about
uniqueneither to Indianorto M. bivittatus. The baselineinformation behavior.
we provide here is a step toward later quantitative and experimental This was followed by observations (n = 98) that were more
research concerned with this poorly understood foraging method. standardized with respect to the information we recorded. Aftereach
ofthese observations, wecollectedthe salticid, theant and the “prey”
1Corresponding author. E-mail: [email protected] (i.e., object snatched from an ant). Salticidswere identified to species,
609
610 THE JOURNAL OF ARACHNOLOGY
ants to genus and lake flies to family. We also recorded whether the oftheant, the ant either stopped momentarily before movingoffin a
salticid was a juvenile or an adult, and we recorded whether adults different direction or itjust slowed down and veered to the side, with
were male or female. Earlier convention (Jackson and Li 2001) is Menemerus continuing to maneuver itselfin front ofthe active ant.
adopted for indicating frequencies ofoccurrence: “usually,” “often,” Attacking: during one ofan ant’s momentary pauses when being
“typically,” and “typical” indicate ca 80% or more. intercepted or else while the ant was attempting to step out of the
RESULTS way, aspidersuddenlyextended its rearlegs, moved its body 1-2 mm
forward, brought itschelicerae intocontactwith anobjectin theant’s
Snatching from ants.—The three Menemerus species, as well as mandiblesand then immediately stepped afewmillimeters backwards
Evarcha culicivora (Wesolowska & Jackson 2003), Harmochirus or to the side, pulling the object out of the ant’s mandibles. In all
brachiatus (Thorell 1877), Hasarius adansoni (Audouin 1826) and instances, the ant released the object when the salticid pulled away.
unidentified species of Hyllus (Koch 1846), Natta (Karsch 1879), Retreating: after extracting an object from the ant’s mandibles,
Myrmarachne (MacLeay 1839), Plexippus (C.L. Koch 1846), and the spider turned and rapidlywalkedaway, usuallynot stoppinguntil
Thyene (Simon 1885), were common on the walls ofbuildings, with about 100-200 mm from the ant column.
many other salticids present in smaller numbers. However, only the Feeding: the spider settled, usually in a space between bricks orin
three Menemerus species were observed snatching from ants. some other secluded location on thewall, and then proceeded to feed
In the records of salticids snatching front ants (n = 98), salticid for 1-10 min. After feeding, the spider dropped the prey and walked
b6omdyml(enng=th1,va1r%i,edMf.rboimvit2tamtums),(nwit=h 61,(61%%), bMeeinnegm3ermums,s2p.7 (n.2)8%t)o aanwoatyh,eraftlearkewhfliychfriotmofttheen arnetts.urnAesd mtoantyheasantfoucrolluamkne falnieds swteorlee
being 4 mm and the majority (n = 63, 64%) being 5 mm. For the sometimes stolen in succession.
majority records of snatching from ants (n = 98), the salticid was There were about 10 instances each for M. congoensis and M.
Menemerussp. n. (78, 80%),with 58 (74%)ofthese 78 recordscoming bivittatus and more than 40 for Menemerus sp. n., in which we
from adult females, 6 (8%) coming from adult males, and 14 (18%) observed,a salticid briefly tracking an ant that had empty mandibles,
comingfromjuveniles. Forall recordsfor Menemeruscongoensis(n = but weneversawa salticid intercepttheseants. Therewerealsoabout
10, 10% of 98) and M. bivittatus (n = 10, 10%), the salticid was a 30 instancesinwhich Menemerussp. n. brieflytracked, butthen failed
juvenile. The ants were undetermined species from the genus to intercept, as well as 9 instances ofseeing a salticid track and then
Crematogaster (n = 72, 73%) and Camponotus (Mayr 1861) (n = intercept an ant that was carryingan object other than a lake fly, but
26, 27%). then moveawaywithout attacking(Menemerussp. n., 5 antscarrying
Observed snatching sequences took place either in the morning plant material and 2 carrying a dead conspecific ant worker; M.
(07:00-11:00 hours, n = 75) or in the late afternoon (17:00- congoensis 2 carrying dead conspecifics).
19:00 hours, n = 23). The objects snatched from ants were usually ,
(90, 92% of 98) dead lake flies (body lengths: 5 to 10 mm) DISCUSSION
(chironomid, n = 77, 79% of 98) and chaoborid (n = 13, 13%). Bhattacharya (1936) provided minima! descriptive detail of
Besides lake flies, adult females of Menemerus sp. n. (body length snatching behavior. He did not indicate howmany times he observed
5 mm)werealsoobserved snatchingan antegg(n = 1),adead mayfly M. bivittatus snatching from ants and he referred to the objects M.
(Ephemeroptera, n = 1), a dead Crematogaster worker (n = 3) and bivittatusstoleassimply“food andeggs” (ant, spider, andobjectsizes
what appeared to be plant material (/; = 3), with all ofthese objects not indicated). Yet his observations on M. bivittatus in India appear
being comparable to lake Hies in size. Menemerus sp. n subsequently to have been similarto ours: tracking, intercepting, attacking(pulling
atethemayflyand theantegg, butreleasedand movedaway fromthe the prey out of the ant’s mandibles) and retreating with the prey
plant material and the dead ant a few seconds after contact. There before feeding.
were also five instances in which Menemerus sp. n. (3 adult females Bhattacharya (1936) also observed M. bivittatus adults, but not
and 2 juveniles) snatched a dead lake fly (not identified to family) juveniles, stalking, capturing, and feeding on house Hies, Musca
from an ant and then, a few seconds later, released the lake fly and domestica(Linnaeus 1758) and he suggested that snatchingprey from
walked away. In all other instances, the salticid ate the lake fly it ants might be the primary foraging tactic ofM. biviattatusjuveniles.
snatched from an ant. Wehesitatetosuggest thatthisistheprimarytacticusedbyanyofthe
Behavioral sequences were similar irrespective ofthedifferent prey, active stages of any of the three Menemerus species we studied
antgenus, Menemerusspecies and, for Menemerussp. n., whether the becausewe observedall stages ofeach ofthe three Menemerusspecies
salticid was a juvenile, an adult male, or an adult female. Five frequently capture and eat free (i.e., not in the mandibles of ants)
behavioral stages were discerned: tracking, intercepting, attacking, living prey by practicing the stalk-and-leap routines that appearto be
retreating, and feeding. typical of many salticid species (Forster 1982; Richman & Jackson
Tracking: a salticid positioned itselfbeside an ant column on the 1992; Jackson & Pollard 1996).
wall of a building, repeatedly fixating (i.e., aligning the gaze of the Our observations suggest instead that snatching from ants is an
corneal lenses ofits anterior-medial eyes) on different individual ants alternative foraging tactic sometimes adopted by small individuals
active in the column and maintaining fixation on each ant for 5 s or (i.e., individuals no more than 6 mm in body length) of Menemerus.
longer by continually turning its body while the ant walked by. The For the smallest of the three Menemerus species we studied (i.e.,
ant beingtracked wasusuallycarryingan object in its mandibles. The Menemerus sp. n.), this included adults of both sexes as well as
mm
salticid usually remained 50-100 from the ant whiletracking and juveniles. However, for M. bivittatusand M. congoensis this included
,
stepped out of the way whenever an ant turned and moved in its onlyjuveniles.
direction. Despite many salticid species being abundant at Mbita Point, the
Intercepting: a spider that had been tracking suddenly began only salticids we saw snatching prey from ants were the three
stepping about and maneuvering into position in front of the ant, Menemerus species. These observations from East Africa, together
effectively blockingtheant’sforward progress. Thisusually happened with Bhattacharya's(1936) recordsfrom India, suggest thatsnatching
only a few seconds after the salticid was first seen tracking, as any from ants may be widespread among species of Menemerus living in
longer delay usually resulted in the ant moving far away from the ant-rich habitats. Further work is needed for determining whether
salticid. When intercepting, Menemerus usually took a veering path this tactic is special to the genus Menemerus and for clarifying the
and approached theantcolumn 20-45° offfrom straightahead ofthe selection pressures thatmighthavefavored theevolution ofsnatching
targeted ant's forward trajectory. When Menemerus stepped in front behavior.
JACKSON ET AL—SPIDERS SNATCH PREY FROM ANTS 611
It is difficult to envisage a salticid needing an ant’s help Forster, L.M. 1982. Vision and prey-catching strategies in jumping
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ACKNOWLDEGMENTS Land, M.F. & D.E. Nilsson. 2002. Animal Eyes. Oxford University
Weareespeciallygrateful to Hans Herren,Christian Borgeimeister, Press, Oxford, UK. 221 pp.
Bart Knols, and Charles Mwenda at the International Centre for Li, D. & R.R. Jackson. 1996. Prey-specific capture behaviour and
Insect Physiology and Ecology for the numerous ways in which they prey preferences of myrmecophagic and araneophagic jumping
supported the research. Godfrey Sune, Stephen Alluoch, Silas Ouko spiders (Araneae: Salticidae). Revue Suisse Zoologie, hors serie,
Orima, and Jane Atieno provided invaluable technical assistance. We 423-436.
gratefully acknowledge support from the National Geographic Nelson, X.J. & R.R. Jackson. 2005. Living with the enemy,jumping
Society (RRJ), the Royal Society of New Zealand (Marsden Fund; spiders that mimic weaver ants. Journal of Arachnology
RRJ, SDP) and James Cook Fellowship (RRJ). For taxonomic 33:813-819.
assistance, we thank Wanda Wesolowska, G.B. Edwards, Roy Nelson, X.J. & R.R. Jackson. 2006a. Compoundmimicryand trading
Snelling and Arthur Harrison. predators by the males of sexually dimorphic Batesian mimics.
Proceedings ofthe Royal Society ofLondon (B) 273:367-372.
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22:565-592. Manuscript received8 August 2007, revised21 April2008.
